Video data transmission processing method, video data sending processing method, apparatus, network system

ABSTRACT

Embodiments of the present invention provide a video data transmission processing method, a video data sending processing method, an apparatus, and a network system. The data transmission processing method includes: receiving a source stream sent from a source transmission network to a target transmission network; performing, according to respective packet loss rates of the source transmission network and the target transmission network as well as error tolerance aid information corresponding to the source stream, error tolerance coding processing on the source stream to obtain an error tolerance stream; and sending the obtained error tolerance stream to the target transmission network.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2010/077526, filed on Sep. 30, 2010, which claims priority toChinese Patent Application No. 200910179726.5, filed on Sep. 30, 2009,both of which are hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to the field of video data transmissiontechnologies, and in particular, to a video data transmission processingmethod, a video data sending processing method, an apparatus, and anetwork system.

BACKGROUND OF THE INVENTION

In an existing video transmission application environment, variousnetworks exist, including wired networks and wireless networks. Thesenetworks have different data error probabilities, that is, thereliability of signal transmission is different. For example, in a videotransmission network, a video stream provided by a video server isforwarded by a media gateway (Media Gateway), and the media gatewayextracts and sends the video substreams required by other networks. Forvideo stream applications, a delay and packet loss in networktransmission may cause that a video packet is unavailable, so thatquality of a decoded video decreases severely. Generally, in a wirednetwork, a packet loss rate is relatively low, and a transmission rateis relatively high. However, a wireless network (the networks such asWLAN, 3G network based on a base station, and GPRS) is the contrary. Ina wired network, the data packet loss rate is relatively low, and packetloss is mainly caused by congestion of routers in the network. However,in a wireless network, a high packet loss rate is caused by limitedbandwidth, high delay, and high bit error rate.

Because the error probability in a wireless environment is far greaterthan that in a wired environment, the video server should provide anerror control function to enable seamless switching among thesedifferent networks when a video user accesses video data. An existingerror control technology includes error tolerance transcoding. That is,a video server provides a stream suitable for a wired network, and thena transcoder is added at the network border so that redundancy suitablefor the target network is provided for the video stream. A video agentis used as a transcoder to decode an original stream and then encode it,which increases complexity of the transcoder, and also increases asystem delay. The existing error control technology further includesredundant frame coding, which aims at using redundant information toprotect a series of compressed images, so that the compressed imageshave the ability to recover from errors or impact caused bycommunication errors on the compressed images is reduced. However, thismethod generates redundant frames in the case of a given packet lossrate, which may cause a waste of network resources. For example, in awired channel from the video server to the first data forwarding nodeand in the wireless channel from the first data forwarding node to thesecond data forwarding node, the error probability of the former channelis lower than that of the latter channel. However, in order for the userafter the second data forwarding node to obtain better video decodingquality, the video server needs to add much redundancy in the stream,thereby causing a waste of bandwidth in the channel from the videoserver to the first data forwarding node.

In the implementation of the present invention, the inventor finds theprior art has at least the following problems: In at least twotransmission networks with different packet loss rates in the prior art,a stream is generated according to a fixed packet loss rate. If thestream is generated according to a high packet loss rate, the redundancyis excessive, and therefore the utilization rate of bandwidth resourcesis low; or, if the stream is generated according to a low packet lossrate, the video quality deteriorates when the network conditions becomeworse.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a video data transmissionprocessing method, a video data sending processing method, an apparatus,and a network system, so as to improve the error tolerance capability ofa stream in different network environments with different packet lossrates.

An embodiment of the present invention provides a video datatransmission processing method, including:

receiving a source stream sent from a source transmission network to atarget transmission network;

performing, according to respective packet loss rates of the sourcetransmission network and the target transmission network as well aserror tolerance aid information corresponding to the source stream,error tolerance coding processing on the source stream to obtain anerror tolerance stream; and

sending the obtained error tolerance stream to the target transmissionnetwork.

An embodiment of the present invention provides a video data sendingprocessing method, including:

obtaining error tolerance aid information corresponding to a sourcestream according to packet loss rates corresponding to at least twotransmission networks in a data transmission network system beforesending the source stream to the data transmission network system, wherethe error tolerance aid information is used by a data forwarding node inthe data transmission network system to perform error tolerance codingprocessing on the received stream to obtain an error tolerance streamfor reference; and

sending the error tolerance aid information to the data forwarding node.

An embodiment of the present invention provides a data forwarding nodedevice, including:

a first receiving module, configured to receive a source stream sentfrom a source transmission network to a target transmission network;

a coding processing module, configured to perform error tolerance codingprocessing on the source stream according to respective packet lossrates of the source transmission network and the target transmissionnetwork as well as error tolerance aid information corresponding to thesource stream to obtain an error tolerance stream; and

a first sending module, configured to send the obtained error tolerancestream to the target transmission network.

An embodiment of the present invention provides a network device,including:

a first obtaining module, configured to obtain error tolerance aidinformation corresponding to a source stream according to packet lossrates corresponding to at least two transmission networks in a datatransmission network system before sending the source stream to the datatransmission network system, where the error tolerance aid informationis used by a data forwarding node in the data transmission networksystem to perform error tolerance coding processing on the receivedstream to obtain an error tolerance stream for reference; and

a second sending module, configured to send the error tolerance aidinformation to the data forwarding node.

An embodiment of the present invention provides a network system,including:

a data forwarding node device, configured to: receive a source streamsent from a source transmission network to a target transmissionnetwork; perform error tolerance coding on the source stream accordingto respective packet loss rates of the source transmission network andthe target transmission network as well as error tolerance aidinformation corresponding to the source stream to obtain an errortolerance stream; and send the obtained error tolerance stream to thetarget transmission network; and

a network device, configured to: obtain error tolerance aid informationcorresponding to a source stream according to packet loss ratescorresponding to at least two transmission networks in a datatransmission network system before sending the source stream to the datatransmission network system; and send the error tolerance aidinformation to the data forwarding node device, where the errortolerance aid information is used by the data forwarding node device inthe data transmission network system to perform error tolerance codingprocessing on the received stream to obtain an error tolerance streamfor reference.

In the video data transmission processing method, video data sendingprocessing method, apparatus, and network system provided in theembodiments of the present invention, the data server obtains errortolerance aid information corresponding to the to-be-sent streamaccording to packet loss rates corresponding to at least twotransmission networks in the data transmission network system.Therefore, according to different packet loss rates of transmissionnetworks, the data forwarding node can use the error tolerance aidinformation to quickly generate the error tolerance stream compliantwith the packet loss characteristics of the subsequent transmissionnetwork, which can improve the error tolerance capability of streams indifferent network environments with different packet loss rates.

BRIEF DESCRIPTION OF THE DRAWINGS

To illustrate the technical solutions in the embodiments of the presentinvention more clearly, the accompanying drawings for describing theembodiments are briefly introduced below. Apparently, the accompanyingdrawings in the following descriptions are merely some embodiments ofthe present invention, and persons of ordinary skill in the art mayfurther derive other drawings according to these accompanying drawingswithout creative efforts.

FIG. 1 is a schematic diagram of a method for extracting and using errortolerance aid information according to an embodiment of the presentinvention;

FIG. 2 is a flow chart of an embodiment of a data sending processingmethod according to the present invention;

FIG. 3 is a flow chart of an embodiment of a data transmissionprocessing method according to the present invention;

FIG. 4 is a schematic diagram of an application scenario of an increasedpacket loss rate in a video transmission process according to anembodiment of the present invention;

FIG. 5 is a schematic diagram of an application scenario of a decreasedpacket loss rate in a video transmission process according to anembodiment of the present invention;

FIG. 6 is a schematic diagram of performance of adding redundancy undera 3% packet loss rate according to an embodiment of the presentinvention;

FIG. 7 is a schematic diagram of performance of adding redundancy undera 5% packet loss rate according to an embodiment of the presentinvention;

FIG. 8 is a schematic diagram of performance of adding redundancy undera 10% packet loss rate according to an embodiment of the presentinvention;

FIG. 9 is a schematic diagram of performance of adding redundancy undera 20% packet loss rate according to an embodiment of the presentinvention;

FIG. 10 is a schematic diagram of using forward error correctiondescription information for FEC redundancy allocation according to amethod embodiment of the present invention;

FIG. 11 is a schematic structure diagram of an embodiment of a dataforwarding node device according to the present invention;

FIG. 12 is a schematic structure diagram of a network device accordingto a first embodiment of the present invention;

FIG. 13 is a schematic structure diagram of a network device accordingto a second embodiment of the present invention; and

FIG. 14 is a schematic composition diagram of an embodiment of a networksystem according to the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

To make the objectives, the technical solutions and the advantages ofthe embodiments of the present invention more comprehensive, thetechnical solutions in the embodiments of the present invention will beclearly and fully described below with reference to the accompanyingdrawings. Apparently, the embodiments to be described are a part ratherthan all of the embodiments of the present invention. All otherembodiments obtained by persons of ordinary skill in the art based onthe embodiments of the present invention without creative efforts shallfall within the protection scope of the present invention.

With the development of network technologies, network convergence may beperformed on various kinds of networks, such as a wired network and awireless network, to form an integrated network system to meet differentrequirements of users. However, different networks have different packetloss rates, and the packet loss in network transmission leads toproblems such as unavailability of a video packet and deterioratesquality of decoded videos severely. To meet the packet loss rate ofdifferent networks and improve the error tolerance capability of astream in network environments with different packet loss rates, it isnecessary to make full and proper use of network resources, providebetter video quality, make fast response to every change, and change theerror tolerance capability of the stream according to actual conditions,for example, change the stream redundancy rate and the forward errorcorrection (Forward Error Correction, FEC for short) protectionstrength.

To sum up, for a case of different packet loss rates of data streams innetwork transmission, each embodiment of the present invention putforwards a coding and transmission solution characterized by scalableerror resilience. FIG. 1 is a schematic diagram of a method forextracting and using error tolerance aid information according to anembodiment of the present invention. As shown in FIG. 1, analysis andcalculation are performed on the coding side first, and detaileddescription information that is generated according to networkenvironments and video characteristics is used to aid in generating asubsequent error tolerance stream. The information is defined as errortolerance aid information. The error tolerance aid information may beembedded into the stream or transmitted to each data forwarding node byother means. Then, considering change of the network in the transmissionprocess, the data forwarding node uses the error tolerance aidinformation to quickly generate an error tolerance stream compliant withthe subsequent network packet loss characteristics according to thepacket loss rate of the subsequent network. In this embodiment, theerror tolerance aid information is introduced, and the data forwardingnode may transcode the stream quickly according to the aid informationand the corresponding packet loss rate, which makes full use of systembandwidth resources. Moreover, low delay and low operation complexityare good for real-time application. In FIG. 1, the data forwarding nodemay be a device such as a streaming server, a media gateway, or arouter; and the error tolerance aid information may be used for adding aredundant frame of the stream and for FEC.

FIG. 2 is a flow chart of an embodiment of a data sending methodaccording to the present invention. As shown in FIG. 2, the methodincludes the following:

Step 100: The data server obtains error tolerance aid informationcorresponding to a source stream according to packet loss ratescorresponding to at least two transmission networks in a datatransmission network system before sending the source stream to the datatransmission network system.

In this embodiment, the data transmission network system includes a dataserver that is used to provide data sources, and further includesmultiple data forwarding nodes that are used to forward sent data, and auser equipment terminal. The data server, the data forwarding nodes, andthe terminal device are connected through various transmission networks.The transmission networks provide a channel for data transmission. Basedon the network convergence technology, at least two transmissionnetworks in the data transmission network system have different packetloss rates. To make a sent video streams adaptable to network packetloss characteristics of different transmission networks and to ensurereliability of data transmission, the data server such as a video serverobtains the error tolerance aid information corresponding to the sentsource stream before sending the video stream to a certain dataforwarding node in the data transmission network system. The errortolerance aid information includes description information about errortolerance data sets that respectively correspond to the respectivepacket loss rates of at least two transmission networks such as thesource transmission network and the target transmission network in thedata transmission network system. The error tolerance data sets areconfigured to identify the error tolerance data that needs to beadjusted in the source stream. Each error tolerance data set indicatedby the description information meets the following condition: An errortolerance data set corresponding to a low packet loss rate is a subsetof an error tolerance data set corresponding to a high packet loss rate.The error tolerance aid information is used by the data forwarding nodein the data transmission network system to perform error tolerancecoding processing on the received stream to obtain the error tolerancestream compliant with the packet loss rate corresponding to thesubsequent transmission network. That is to say, the data forwardingnode can perform quick transcoding on the packet loss rate of thesubsequent transmission network of the data forwarding node according tothe error tolerance aid information, and uses the error tolerance aidinformation to quickly generate the error tolerance stream compliantwith the subsequent network packet loss characteristics.

The video server needs to generate the error tolerance aid informationaccording to the packet loss rates corresponding to at least twotransmission networks in the data transmission network system. That isto say, the information described by the error tolerance aid informationmay be adaptable to transmission networks of different packet lossrates. After receiving the stream sent by a previous transmissionnetwork, with the aid of the error tolerance aid information, the dataforwarding node can find error tolerance operation rules correspondingto two packet loss rates of the previous transmission network and thenext transmission network, and perform error tolerance transcodingaccording to an indication to generate an error tolerance stream.Definitely, the data streams of different characteristics shouldcorrespond to different error tolerance aid information, so as to meetrequirements. In this embodiment, the data server may be a device suchas a video server, a video-on-demand server.

Step 101: The data server sends the error tolerance aid information tothe data forwarding node.

After obtaining the error tolerance aid information corresponding to thevideo stream to be sent, the data server sends the error tolerance aidinformation to each data forwarding node in the data transmissionnetwork system for the data forwarding node to perform error tolerancecoding.

Before sending the video data to the data forwarding node that isconnected with the data server, in order to adapt to the packet lossrate of the transmission network between the data forwarding nodes, thedata server should perform error tolerance coding on the source streamaccording to the previously obtained error tolerance aid information.After generating the error tolerance stream corresponding to the sourcestream according to the error tolerance aid information and the packetloss rate corresponding to the transmission network between the dataforwarding nodes, the data server may send the error tolerance streamtogether with the error tolerance aid information to the data forwardingnode. Definitely, the error tolerance stream and the error tolerance aidinformation may also be sent separately and independently.

In the data sending processing method provided in this embodiment, thedata server obtains error tolerance aid information corresponding to theto-be-sent stream according to packet loss rates corresponding to atleast two transmission networks in the data transmission network system,and sends the error tolerance aid information to the data forwardingnode. Therefore, according to different packet loss rates oftransmission networks, the data forwarding node can use the errortolerance aid information to quickly generate the error tolerance streamcompliant with the packet loss characteristics of the subsequenttransmission network, which can improve the error tolerance capabilityof a stream in network environments with different packet loss rates.Moreover, low delay and low operation complexity are good for real-timeapplication.

FIG. 3 is a flow chart of an embodiment of a data transmission methodaccording to the present invention. As shown in FIG. 3, the methodincludes the following:

Step 200: Receive a source stream sent from a source transmissionnetwork to a target transmission network.

According to the packet loss rates corresponding to at least twotransmission networks in the data transmission network system such asthe source transmission network and the target transmission network ofthe data forwarding node, the data server obtains the error toleranceaid information corresponding to the source stream, and sends the errortolerance aid information to the data forwarding node, and then the dataforwarding node receives the error tolerance aid information. The sourcetransmission network and the target transmission network involved inthis embodiment refer to the transmission networks on both sides of thedata forwarding node from the perspective of the flow direction of thedata. The source stream received by the data forwarding node may be sentby the data server or by other data forwarding nodes. For example, thedata server sends the source stream to the terminal device through thedata forwarding node. In this embodiment, the transmission networkbetween the data server and the data forwarding node may be called asource transmission network, and the transmission network between thedata forwarding node and the terminal device may be called a targettransmission network. That is to say, the source stream sent by the dataserver is sent through the source transmission network to the targettransmission network.

Step 201: Perform error tolerance coding on the source stream accordingto respective packet loss rates of the source transmission network andthe target transmission network as well as error tolerance aidinformation corresponding to the source stream to obtain an errortolerance stream.

When the network is constructed, the data forwarding node alreadyacquires the respective packet loss rates of the source transmissionnetwork and the target transmission network. Therefore, after receivingthe source stream sent by the data server, the data forwarding node mayperform fast transcoding on the source stream according to therespective packet loss rates of the source transmission network and thetarget transmission network, and with reference to the error toleranceaid information. The data forwarding node uses the error tolerance aidinformation to quickly generate the error tolerance stream compliantwith the subsequent network packet loss characteristics, makes fastresponse to change of the packet loss rate, and changes the errortolerance capability of the stream according to actual conditions, forexample, changes the stream redundancy rate and the FEC protectionstrength according to actual conditions. The error tolerance codingprocess should be different from the video coding process. The errortolerance coding is a relatively simple operation of changing the errortolerance capability, and may a process of copying the stream directlyor adding some codes.

Step 202: Send the obtained error tolerance stream to the targettransmission network.

After obtaining the error tolerance stream of the subsequenttransmission network, the data forwarding node sends the error tolerancestream to the terminal device or other data forwarding nodes through thetarget transmission network. In addition, the data forwarding node mayfurther forward the error tolerance aid information and the errortolerance stream together or separately to other data forwarding nodes.

Through the data transmission method provided in this embodiment,according to the error tolerance aid information sent by the data serverand corresponding to the data stream, the data forwarding node performserror tolerance coding on the stream needed to be forwarded to obtain anerror tolerance stream, so as to adapt to the network characteristics ofthe packet loss rate of the subsequent transmission network. Networkresources can be made full and proper use of; fast response may be madeto every change; and the error tolerance capability of the stream ischanged according to actual conditions.

The error tolerance aid information involved in all embodiments abovemay be adaptable to a variety of application environments. The followinggives application examples of using the error tolerance aid informationto adjust redundant frames adaptively or perform FEC protection.

In an embodiment of adjusting the redundant frames adaptively, accordingto the packet loss rates corresponding to at least two transmissionnetworks in the data transmission network system, the data serverobtains the error tolerance aid information that is used by the dataforwarding node in adjusting redundant frames in the received streamadaptively to obtain the error tolerance stream compliant with thepacket loss rate of the subsequent transmission network. The errortolerance aid information includes description information about theredundant frame sets corresponding to the at least two transmissionnetworks respectively in the data transmission network systems. Theredundant frame sets are configured to identify data frames whoseredundant frames need to be generated among multiple data frames in thestream. Each redundant frame set indicated by the descriptioninformation meets the following condition: A redundant frame setcorresponding to a low packet loss rate is a subset of a redundant frameset corresponding to a high packet loss rate. Therefore, the redundantframe set is an example of the error tolerance data set in the foregoingembodiment. For the data forwarding node, according to the respectivepacket loss rates of the source transmission network and the targettransmission network as well as the error tolerance aid informationcorresponding to the source stream, the data forwarding node may adjustthe redundant frames adaptively for multiple data frames included in thereceived source stream, so as to obtain an error tolerance streamcomplaint with the packet loss rate of the target transmission network.

In this embodiment, the error tolerance aid information may be appliedto add redundant frames in the stream adaptively. The detailedimplementation steps are as follows. First, estimate the overallsource-and-channel distortion in the coding process of the data server,and extract the redundancy description information of each frame underdifferent packet loss rates; second, add such tiny amount of informationinto the stream for transmission, or transmit the information to thedata forwarding node separately; and then, the data forwarding node mayadd or delete redundant frames adaptively for different packet lossrates according to the redundancy description information.

The foregoing redundancy description information is an example of theerror tolerance aid information. The process of extracting suchinformation includes the following. First, calculate source distortioninformation and channel distortion information corresponding to eachdata frame in the stream with respect to packet loss rates of at leasttwo transmission networks in the case of generating no redundant frameand in the case of generating redundant frames respectively; afterward,a rate-distortion model is applied to judge whether redundant frames ofthe data frames corresponding to the calculated source distortioninformation and channel distortion information need to be generatedunder the corresponding packet loss rate condition to obtain a judgmentresult, namely, using a rate-distortion model to select thebest-performance mode of generating redundant frames for differentpacket loss rates respectively; finally, according to the judgmentresult, obtain the description information that organizes and describesredundant frame sets corresponding to different packet loss ratesrespectively. The following gives more details.

The source distortion and the channel distortion are estimated by usingan improved recursive optimal per-pixel estimate (Recursive OptimalPer-pixel Estimate, ROPE for short) algorithm. It is assumed that thestream of a video frame is encapsulated into a packet in thetransmission process. Therefore, in a case that the current packet lossrate is p, the probability of losing each video frame is also p. If thevalue of pixel i in frame n of an original video sequence is f_(n) ^(i),the restructured value on the coding side is {circumflex over (f)}_(n)^(i), and the restructured value on the decoding side is {tilde over(f)}_(n) ^(i), and therefore, the overall source-and-channel distortionmay be expressed as a mean square error of f_(n) ^(i) and {tilde over(f)}_(n) ^(i). The coding side is unable to obtain the preciserestructured value on the decoding side after the stream is transmittedby an erroneous channel. Therefore, {tilde over (f)}_(n) ^(i) may beregarded as a random signal under an erroneous channel, and the overallsource-and-channel distortion changes to:

$\begin{matrix}\begin{matrix}{{E\{ d_{n}^{i} )} = {E\{ ( {f_{n}^{i} - {\overset{\sim}{f}}_{n}^{i}} )^{2} \}}} \\{= {E\{ ( {f_{n}^{i} - {\hat{f}}_{n}^{i} + {\hat{f}}_{n}^{i} - {\overset{\sim}{f}}_{n}^{i}} )^{2} \}}} \\{= {E\{ {( {f_{n}^{i} - {\hat{f}}_{n}^{i}} )^{2} + ( {{\hat{f}}_{n}^{i} - {\overset{\sim}{f}}_{n}^{i}} )^{2} + {2( {f_{n}^{i} - {\hat{f}}_{n}^{i}} ){\bullet( {{\hat{f}}_{n}^{i} - {\overset{\sim}{f}}_{n}^{i}} )}}} \}}} \\{= {( {f_{n}^{i} - {\hat{f}}_{n}^{i}} )^{2} + {E\{ ( {{\hat{f}}_{n}^{i} - {\overset{\sim}{f}}_{n}^{i}} )^{2} \}} + {E\{ {( {f_{n}^{i} - {\hat{f}}_{n}^{i}} ){\bullet( {{\hat{f}}_{n}^{i} - {\overset{\sim}{f}}_{n}^{i}} )}} \}}}}\end{matrix} & (1) \\{and} & \; \\\begin{matrix}{{E\{ d_{n}^{i} \}} = {E\{ ( {f_{n}^{i} - {\overset{\sim}{f}}_{n}^{i}} )^{2} \}}} \\{= {( f_{n}^{i}\; )^{2} + {E\{ ( {\overset{\sim}{f}}_{n}^{i} )^{2} \}} + {2f_{n}^{i}\bullet\; E\{ {\overset{\sim}{f}}_{n}^{i} \}}}}\end{matrix} & (2)\end{matrix}$

(f_(n) ^(i)−{circumflex over (f)}_(n) ^(i))² represents sourcedistortion; E{({circumflex over (f)}_(n) ^(i)−{tilde over (f)}_(n)^(i))²} represents channel distortion; and the third term in formula (1)is a correlation of source distortion with channel distortion. Inaddition, formula (2) gives another expression mode of the overallsource-and-channel distortion. It can be seen that, the overallsource-and-channel distortion is a result of estimating the first-ordermoment and the second-order moment of {tilde over (f)}_(n) ^(i). Anembodiment of the present invention provides a method for estimating thefirst-order moment and the second-order moment based on pixels—ROPE. Itis assumed that an error concealment method used on the decoding side isFC, then the first-order moment and the second-order moment may becalculated recursively in a pixel coding mode:

Pixels in an intra-frame prediction (Intra prediction, Intra for short)code block are as follows:E{{tilde over (f)} _(n) ^(i) }{I}=(1−p){circumflex over (f)} _(n) ^(i)+pE{{tilde over (f)} _(n-1) ^(i)}  (3)E{({tilde over (f)} _(n) ^(i))² }{I}=(1−p)({circumflex over (f)} _(n)^(i))² +pE{({tilde over (f)} _(n-1) ^(i))²}  (4)

Pixels in an inter-frame prediction (Inter prediction, Inter for short)code block are as follows:

$\begin{matrix}{{E\{ {\overset{\sim}{f}}_{n}^{i} \}\{ P \}} = {{( {1 - p} )( {{\hat{e}}_{n}^{i} + {E\{ {\overset{\sim}{f}}_{n - 1}^{j} \}}} )} + {{pE}\{ {\overset{\sim}{f}}_{{n - 1}\;}^{i} \}}}} & (5) \\\begin{matrix}{{E\{ ( {\overset{\sim}{f}}_{n}^{i} )^{2} \}\{ P \}} = {{( {1 - p} )E\{ ( {{\hat{e}}_{n}^{i} + {E\{ {\overset{\sim}{f}}_{n - 1}^{j} \}}} )^{2} \}} + {{pE}\{ ( {\overset{\sim}{f}}_{n - 1}^{i} )^{2} \}}}} \\{= {{( {1 - p} )( {( {\hat{e}}_{n}^{i} )^{2} + {2{\hat{e}}_{n}^{i}E\{ {\overset{\sim}{f}}_{n - 1}^{j} \}} + {E\{ ( {\overset{\sim}{f}}_{n - 1}^{j} )^{2} \}}} )} +}} \\{{pE}\{ ( {\overset{\sim}{f}}_{n - 1}^{i} )^{2} \}}\end{matrix} & (6)\end{matrix}$

In the Inter coding, pixel i of the current frame is a pixel in locationj and is obtained according to motion compensation by referring to theprevious frame (reference frame). The prediction error e_(n) ^(i) isquantized into ê_(n) ^(i).

In the process of calculating the overall source-and-channel distortionof pixels of the current frame in this embodiment, the case that aredundant frame of the current frame exists must be taken intoconsideration. Unlike the ROPE method, the mode of a pixel in theredundant frame at this time may be different from the mode of the pixelin the same location of the current frame. Even if the Inter mode is thesame, the motion vector may differ. Therefore, when calculating thefirst-order moment and the second-order moment of the pixel, thisembodiment puts forward the following recursion formula in considerationof combinations of such modes:

(1) Pixels of both the redundant frame and the current frame are in anIntra block:E{({tilde over (f)} _(n) ^(i))}{I}=(1−p){circumflex over (f)} _(n) ^(i)+p(1−p){circumflex over (f)} _(r) _(n) ^(i) +p ² E{{tilde over (f)}_(n-1) ^(i)}  (7)E{({tilde over (f)} _(n) ^(i))² }{I}=(1−p)({circumflex over (f)} _(n)^(i))² +p(1−p)({circumflex over (f)} _(r) _(n) ^(i))² +p ² E{({tildeover (f)} _(n-1) ^(i))²}  (8)

(2) Pixels of both the redundant frame and the current frame are in anInter block:

$\begin{matrix}{{E\{ {\overset{\sim}{f}}_{n}^{i} \}\{ {PP} \}} = {{( {1 - p} )( {{\hat{e}}_{n}^{i} + {E\{ {\overset{\sim}{f}}_{n - 1}^{j} \}}} )} + {{p( {1 - p} )}E\{ ( {{\hat{e}}_{r_{n}}^{i} + {E\{ {\overset{\sim}{f}}_{n - 1}^{j_{r}} \}}} )^{2} \}} + {p^{2}E\{ ( {\overset{\sim}{f}}_{n - 1}^{i} )^{2} \}}}} & (9) \\\begin{matrix}{\mspace{50mu}{{E\{ ( {\overset{\sim}{f}}_{n}^{i} )^{2} \}\{ {PP} \}} = {{( {1 - p} )E\{ ( {{\hat{e}}_{n}^{i} + {E\{ {\overset{\sim}{f}}_{n - 1}^{j} \}}} )^{2} \}} +}}} \\{{{p( {1 - p} )}E\{ ( {{\hat{e}}_{r_{n}}^{i} + {E\{ {\overset{\sim}{f}}_{n - 1}^{j_{r}} \}}} )^{2} \}} + {p^{2}E\{ ( {\overset{\sim}{f}}_{n - 1}^{i} )^{2} \}}} \\{= {{( {1 - p} )( {( {\hat{e}}_{n\;}^{i} )^{2} + {2{\hat{e}}_{n}^{i}E\{ {\overset{\sim}{f}}_{n - 1}^{j} \}} + {E\{ ( {\overset{\sim}{f}}_{n - 1}^{j} )^{2} \}}} )} +}} \\{{{p( {1 - p} )}( {( {\hat{e}}_{r_{n}}^{i} )^{2} + {2{\hat{e}}_{r_{n}}^{i}E\{ {\overset{\sim}{f}}_{n - 1}^{j_{r}} \}} + {E\{ ( {\overset{\sim}{f}}_{n - 1}^{j_{r}} )^{2} \}}} )} +} \\{p^{2}E\{ ( {\overset{\sim}{f}}_{n - 1}^{i} )^{2} \}}\end{matrix} & (10)\end{matrix}$

(3) Pixels of the redundant frame are in an Intra block, and pixels ofthe current frame are in an Inter block:

$\begin{matrix}{\mspace{79mu}{{E\{ {\overset{\sim}{f}}_{n}^{i} \}\{ {IP} \}} = {{( {1 - p} )( {{\hat{e}}_{n}^{i} + {E\{ {\overset{\sim}{f}}_{n - 1}^{j} \}}} )} + {{p( {1 - p} )}{\hat{f}}_{r_{n}}^{i}} + {p^{2}E\{ {\overset{\sim}{f}}_{n - 1}^{i} \}}}}} & (11) \\{{E\{ ( {\overset{\sim}{f}}_{n}^{i} )^{2} \}\{ {IP} \}} = {{( {1 - p} )( {( {\hat{e}}_{n}^{i} )^{2} + {2{\hat{e}}_{n}^{i}E\{ {\overset{\sim}{f}}_{n - 1}^{j} \}} + {E\{ ( {\overset{\sim}{f}}_{n - 1}^{j} )^{2} \}}} )} + {{p( {1 - p} )}( {\hat{f}}_{r_{n}}^{i} )^{2}} + {p^{2}E\{ ( {\hat{f}}_{n - 1}^{i} )^{2} \}}}} & (12)\end{matrix}$

(4) Pixels of the redundant frame are in an Inter block, and pixels ofthe current frame are in an Intra block:

$\begin{matrix}{{E\{ {\overset{\sim}{f}}_{n}^{i} \}\{ {PI} \}} = {{( {1 - p} ){\hat{f}}_{n}^{i}} + {{p( {1 - p} )}E\{ ( {{\hat{e}}_{r_{n}}^{i} + {E\{ {\overset{\sim}{f}}_{n - 1}^{j_{r}} \}}} )^{2} \}} + {p^{2}E\{ ( {\overset{\sim}{f}}_{n - 1}^{i} )^{2} \}}}} & (13) \\\begin{matrix}{\mspace{20mu}{{E\{ ( {\overset{\sim}{f}}_{n}^{i} )^{2} \}\{ {PI} \}} = {{( {1 - p} )( {\hat{f}}_{n}^{i} )^{2}} + {{p( {1 - p} )}E\{ ( {{\hat{e}}_{r_{n}}^{i} + {E\{ {\overset{\sim}{f}}_{n - 1}^{j_{r}} \}}} )^{2} \}} +}}} \\{p^{2}E\{ ( {\overset{\sim}{f}}_{n - 1}^{i} )^{2} \}} \\{= {{( {1 - p} )( {\hat{f}}_{n}^{i} )^{2}} + {p( {1 - p} )}}} \\{( {( {\hat{e}}_{r_{n}}^{i} )^{2} + {2{\hat{e}}_{r_{n}}^{i}E\{ {\overset{\sim}{f}}_{n - 1}^{j_{r}} \}} + {E\{ ( {\overset{\sim}{f}}_{n - 1}^{j_{r}} )^{2} \}}} ) +} \\{p^{2}E\{ ( {\overset{\sim}{f}}_{n - 1}^{i} )^{2} \}}\end{matrix} & (14)\end{matrix}$

In the current frame, pixel i of the Inter block uses pixel j in theprevious frame (reference frame) as a reference, and the predictionerror e_(n) ^(i) is quantized as ê_(n) ^(i); in a redundant frame, pixeli of the Inter block uses pixel j_(r) in the previous frame (referenceframe) as a reference, and the prediction error e_(r) _(n) ^(i) isquantized as ê_(r) _(n) ^(i).

The following considers the overall source-and-channel distortion of anentire frame (M is the number of pixels in each frame):

$\begin{matrix}\begin{matrix}{D = {\sum\limits_{i = 0}^{M}{E\{ d_{n}^{i} \}}}} \\{= {\sum\limits_{i = 0}^{M}\{ {( f_{n}^{i} )^{2} + {E\{ ( {\overset{\sim}{f}}_{n}^{i} )^{2} \}} + {2f_{n}^{i}E\{ {\overset{\sim}{f}}_{n}^{i} \}}} \}}}\end{matrix} & (15)\end{matrix}$

The overall source-and-channel distortion of the current frame in thecase of generating redundant frames and in the case of generating noredundant frame may be calculated respectively by using formula (15) andformulas (3)-(14). Further, the framing of no redundant frame and theframing of a redundant frame are regarded as two modes, respectivelymode 1, and mode 2. The mode may be selected according torate-distortion criteria:RD cos t(mode1)=D ₁ +λR ₁  (16)RD cos t(mode2)=D ₂ +λR ₂  (17)

D₁ is the overall source-and-channel distortion of the frame without anyredundant frame and is calculated by using formulas (3)-(6) and formula(15); and D₂ is the overall source-and-channel distortion of the framewith a redundant frame and is calculated by using formulas (7)-(14) andformula (15). R₁ is the bit rate of the current frame, and R₂ is thetotal bit rate when a redundant frame is included. λ in the formulas isa Lagrange parameter when an error exists. For the detailed calculationmethod, reference may be made to the following embodiment. When the costfunction value of mode 1 is greater than the cost function value of mode2, a redundant frame may be allocated to the current frame.

According to the method above, different redundant frame sets may begenerated for different packet loss rates:

_(X %) ={P _(r) _(—) _(X) |X=3,5,10,20}  (18)

_(X %) is a set of redundant frames P_(r) _(—) _(X) gene rated when thepacket loss rate is X %.

To make the generated redundant frames be scalable under differentpacket loss rates, such sets must meet the following condition:{

_(3%) ⊂

_(5%) ⊂

_(10%) ⊂

_(20%)}  (19)

In the practical operation process, a procedure of generating redundantinformation during coding is: First, generate a redundant frame set

_(20%) under a 20% packet loss rate; afterward, add the followingconstraint to each frame under a packet loss rate of 10%, 5%, and 3%successively: if a redundant frame of the frame is generated in a casethat the packet loss rate is higher than the current packet loss rate, aredundant frame of the frame is generated under the current packet lossrate; otherwise, no redundant frame of the frame is generated.Experiments show that, after such a constraint is added, compared withthe case that the redundant frame is generated for each packet loss rateindependently, the performance does not deteriorate obviously. Thendescribe and transmit information about a specific frame whose redundantframe needs to be generated under specific packet loss rates, so thatthe data forwarding node may adapt to different packet loss rates byusing such information to add or delete a redundant frame in a streamquickly.

According to the respective packet loss rates of the source transmissionnetwork and the target transmission network as well as the errortolerance aid information corresponding to the source stream, the dataforwarding node adjusts the redundant frames adaptively for multipledata frames included in the source stream. Specifically, the adjustmentmay include the following three cases:

If the first packet loss rate corresponding to the source transmissionnetwork is less than the second packet loss rate corresponding to thetarget transmission network, according to the first redundant frame setcorresponding to the first packet loss rate and the second redundantframe set corresponding to the second packet loss rate that areindicated in the description information, the redundant frames whichexist in the second redundant frame set but do not exist in the firstredundant frame set are added into the source stream that carries theredundant frame corresponding to the first packet loss rate. FIG. 4 is aschematic diagram of an application scenario of an increased packet lossrate in a video transmission process according to an embodiment of thepresent invention. As shown in FIG. 4, the video server generateslow-redundancy stream compliant with the current packet loss rate (3%)and generates redundancy description information. For higher packet lossrates (such as 5% and 20%) in the subsequent transmission network, thedata forwarding node determines the frame whose redundant frame isrequired to be added but is lacking under the current packet loss rate(5%, 20%), and then adds a redundant frame for such a frame through suchoperations as copying the frame or generating duplicates of differentquality. This operation has low complexity, may ensure the bestefficiency of the entire system, and improves quality of transmittingvideos.

If the first packet loss rate corresponding to the source transmissionnetwork is greater than the second packet loss rate corresponding to thetarget transmission network, according to the first redundant frame setcorresponding to the first packet loss rate and the second redundantframe set corresponding to the second packet loss rate that areindicated in the description information, the redundant frames whichexist in the first redundant frame set but do not exist in the secondredundant frame set are discarded from the source stream that carriesthe redundant frame corresponding to the first packet loss rate. FIG. 5is a schematic diagram of an application scenario of a decreased packetloss rate in a video transmission process according to an embodiment ofthe present invention. As shown in FIG. 5, the video server generatesthe stream corresponding to the highest packet loss rate (20%) andgenerates redundancy description information. The correspondingredundant frame may be discarded from the stream according to the packetloss rate at the time of switching to a channel that has a relativelylow packet loss rate. For example, the first transcoder (namely, dataforwarding node) converts the high-redundancy stream into a stream thatis suitable for transmission in a wired local area network (with a 3%packet loss rate); the second transcoder transmits the high-redundancystream directly, or converts the high-redundancy stream into asub-high-redundancy stream (with a 10% packet loss rate) and transmitsit to a base station; and the third transcoder converts thehigh-redundancy stream into a low-redundancy stream (with a 5% packetloss rate) and transmits it to a wireless node. In such a solution,although the stream stored in the video server has the greatestredundancy rate, it is not necessary to generate any redundant frame byencoding again, and the flexible error resilience may be provided, whichis noticeably beneficial for the efficiency of the entire system.

If the first packet loss rate corresponding to the source transmissionnetwork is equal to the second packet loss rate corresponding to thetarget transmission network, the data may be forwarded directly withoutany adjustment.

In this embodiment, a pixel-based distortion estimation algorithm isused; the redundant frames can be allocated adaptively and precisely,and then a scalable constraint is added, so that a redundancy withscalable error resilience is generated. Further, a tiny number of bits(such as 3 bits) are used to record redundancy description informationfor each frame. Specifically, the redundancy description information maybe coded into the data of each frame, or a group of pictures (Group OfPictures, GOP for short) or a video is described uniformly. Thedescription information is coded into a head end of the GOP or a headend of the video, so that the bandwidth efficiency of the entiretransmission system reaches the highest level during the applications ofdifferent packet loss rates.

The following is an experiment for the application where the packet lossrate in the foregoing embodiment increases. The experiment environmentis as follows: The experiment platform is H.264/AVC reference softwareJM 10.2; the sequence is Foreman; the video size is QCIF; the frame rateis 15 Hz; the quantization parameter (QP)=20, 24, 28, 32, 36, and 40;the Intra period is 40; the GOP structure is IPPP . . . ; 4000 framesare encoded; the packet loss rate is 3%, 5%, 10%, and 20% respectively,and in the packet discarding tool used in this embodiment, a frame is apacket; repeated decoding: under different packet loss rates, the packetloss file is offset randomly; the decoding is performed for three times,and the average value of the peak signal-to-noise ratios (PeakSignal-to-Noise Ratios, PSNRs for short) is taken.

The stream generated through the foregoing different quantizationparameters QPs is processed with respect to specific packet loss ratesto obtain a rate-distortion (Rate-Distortion, RD for short) curve. Theaverage PSNR difference value between two curves may be calculated byusing the first four QP points and the method provided in the embodimentof the present invention.

First, in the stream that includes no redundancy, a redundant framecorresponding to the packet loss rate is added according to thealgorithm in the foregoing embodiment. Table 1 illustrates enhancementof performance compared between this stream and a stream where noredundant frame is added. The 0% vs X % line illustrates enhancement ofperformance compared between a stream that is generated under an X %packet loss rate and includes a redundant frame and a stream thatincludes no redundant frame under an X % packet loss rate. For example,with the channel packet loss rate being 3%, if redundancy is addedaccording to the redundant frame adding mode corresponding to a 3%packet loss rate in the redundant frame aid information, the performanceis 0.84 dB higher than the performance in the case with no redundantframe being added. Therefore, the stream that is generated through thisalgorithm and includes a redundant frame has better performance underdifferent packet loss rates. Moreover, with increase of the packet lossrate, the performance enhancement is more noticeable. For a low packetloss rate (3%), nearly 1 dB objective quality enhancement accomplishablemay be obtained; for a high packet loss rate (20%), nearly 8 dBobjective quality enhancement accomplishable may be obtained.

TABLE 1 Comparison of performance of redundant frames under differentpacket loss rates ΔPSNR(dB) ΔBitRate(%) 0% vs 3% 0.84 −16.82 0% vs 5%2.42 −45.75 0% vs 10% 5.59 −99.97 0% vs 20% 7.62 <−100.00

Secondly, in application, to reflect the performance of scalableredundant frames under different packet loss rates in the foregoingembodiments, only streams with a small amount of redundancy are stored,and then redundancy is added adaptively according to the actual packetloss rate of the transmission channel by using the method according tothe foregoing embodiments. In Table 2, the Y % vs X % line showsperformance comparison when the channel packet loss rate is X %, betweenperformance of directly transmitting a redundant stream generated undera Y % packet loss rate, and performance of transmitting a redundantstream into which redundancy is adaptively added for the purpose ofadapting to a X % packet loss rate. For example, as shown in the 5% vs10% line, when the channel packet loss rate is 10%, if redundancydescription information is used to add redundancy and generate a streamcompliant with a 10% packet loss rate, the performance of transmittingthe stream is 1.05 dB higher than the performance of directlytransmitting the stream generated when the packet loss rate is 5%.Moreover, the higher the channel packet loss rate is, the morenoticeable the performance enhancement is. For a medium packet loss rate(10%), nearly 1 dB objective quality enhancement may be obtained for ahigh packet loss rate (20%), nearly 0.7 dB objective quality enhancementmay be obtained. The experiment result shows that the redundant framesets generated under different packet loss rates according to thisalgorithm are scalable. That is, redundant frames may be added quicklyand adaptively according to the corresponding packet loss rate toimprove the decoding quality.

TABLE 2 Comparison of scalability performance of redundant frames underdifferent packet loss rates ΔPSNR(dB) ΔBitRate(%)  5% vs 10% 1.05 −18.3310% vs 20% 0.71 −18.47

Thirdly, Table 3 shows performance comparison between error toleranceprotection conducted by using redundancy description information anderror tolerance protection conducted in an adaptive intra-frame refreshmode. Each line shows decoding performance comparison of streams underdifferent packet loss rates when the two modes are used to perform errortolerance protection. Under a low packet loss rate, the performance ofthe algorithm in this embodiment decreases slightly; under a high packetloss rate, however, the performance of the algorithm in this embodimentincreases. Considering the coding complexity of the algorithm on thewhole, the intra-frame refresh transcoding performs concatenateddecoding and coding operations in the transcoder, and the complexity ishigh. However, it is merely required to perform the operation of copyingframes in the transcoder in the embodiment of the present invention, andthe complexity is relatively low. It should be noted that: When theadaptive intra-frame refresh coding mode selection algorithm is used intranscoding, the performance is theoretically lower than the performancebeing achieved by using the adaptive intra-frame refresh method providedhere. The reason is that the input in the transcoding process is arestructuring of a compressed stream, and, after the restructuring isencoded again, the performance is lower than the performance of usingthe intra-frame refresh mode selection algorithm at the time of encodingthe original sequence directly. Therefore, according to the embodimentof the present invention, the performance of the algorithm for using theredundancy description information to perform error tolerance protectionmay be further improved if compared with that of the infra-frame refreshused in the transcoding process.

TABLE 3 Performance comparison between adaptive adding of redundantframes and adaptive intra-frame refresh ARP vs AIR ΔPSNR(dB) ΔBitRate(%)At PLR 3% −0.31 6.89 At PLR 5% −0.02 1.97 At PLR 10% 0.89 −17.65 At PLR20% 0.59 −14.70

FIG. 6 is a schematic diagram of performance of adding redundancy undera 3% packet loss rate according to an embodiment of the presentinvention; FIG. 7 is a schematic diagram of performance of addingredundancy under a 5% packet loss rate according to an embodiment of thepresent invention; FIG. 8 is a schematic diagram of performance ofadding redundancy under a 10% packet loss rate according to anembodiment of the present invention; FIG. 9 is a schematic diagram ofperformance of adding redundancy under a 20% packet loss rate accordingto an embodiment of the present invention. FIG. 6 to FIG. 9 showperformance comparison of a test sequence named “Foreman” underdifferent packet loss rates to test the impact caused by addingredundancy adaptively according to the redundancy descriptioninformation, and the error tolerance protection performed in an adaptiveintra-frame refresh mode when the resolution of the video is 176×144.rdtYlostX is an RD curve of decoding a stream under an X % packet lossrate, where the stream is generated according to redundancy descriptioninformation of a Y % packet loss rate; and air_X % is an RD curve ofdecoding a stream under an X % packet loss rate after an intra-framerefresh coding mode is selected on the coding side by using X % as atarget packet loss rate.

It can be more visually seen from the foregoing drawings that, thebenefits brought by the embodiments of the present invention include thefollowing. The higher the packet loss rate is, the greater impact on thestreams without redundancy is; however, under a low packet loss rate,few packets are lost, and the performance enhanced by adding redundantframes is limited. Therefore, the objective quality enhancement broughtby the embodiments of the present invention under a high packet lossrate is greater than that under a low packet loss rate. The objectivequality enhancement brought by adding redundant frames under a low bitrate is less than that under a high bit rate. Because the quality of avideo is low under a low bit rate, the nuances between the previousframe and the next frame are eliminated by great quantization. At thistime, the effect of using an error concealment method to conceal lostframes is not too bad. Therefore, adding redundant frames cannot muchenhance the objective quality. However, under a high bit rate, using theerror concealment method to conceal the lost frames is not good. At thistime, adding redundant frames enhances the video quality greatly. Fordifferent packet loss rates, different numbers of redundant frames needto be added. For example, under a 10% packet loss rate, if the redundantframe adding policy corresponding to the 5% packet loss rate is used,there is still potentiality of enhancing performance. At this time, abetter policy is to use the redundant frame adding policy correspondingto the 10% packet loss rate. Compared with the adaptive intra-framerefresh coding mode selection algorithm, the algorithm in thisembodiment does not deteriorate the coding performance obviously. Undera low packet loss rate, the performance of the algorithm in theembodiment of the present invention decreases slightly; under a highpacket loss rate, however, the performance of the algorithm in theembodiment of the present invention is superior. The complexity of thealgorithm in the embodiment of the present invention is much lower thanthe complexity of the intra-frame refresh.

For an embodiment of FEC protection, the data server obtains, accordingto the packet loss rates corresponding to at least two transmissionnetworks in the data transmission network system, the error toleranceaid information for the data forwarding node to adjust forward errorcorrection redundancy for each data source block (Source Block, whichrefers to a data unit for performing FEC protection uniformly and is acombination of one or multiple packets) in the received stream to obtainthe error tolerance stream compliant with the packet loss rate of thesubsequent transmission network. The error tolerance aid informationincludes forward error correction description information about theforward error correction sets that correspond to the respective packetloss rates of the source transmission network and the targettransmission network respectively. The forward error correction setincludes the forward error correction redundancy that needs to beallocated to each data source block under different packet loss rates,and each forward error correction set that is indicated in the forwarderror correction description information meets the following condition:A forward error correction set corresponding to a low packet loss rateis a subset of a forward error correction set corresponding to a highpacket loss rate. Therefore, the forward error correction set is anexample of the error tolerance data set in the foregoing embodiment. TheFEC description information put forward in this embodiment may provideassistance for FEC. The detailed implementation steps are as follows:First, at the same time of generating a video stream, the data serversuch as video server generates FEC description information, so as toindicate the FEC redundancy that needs to be actually allocated to eachdata source block under different packet loss rates; moreover, in orderto make the FEC description information support the operation ofscalable FEC adjustment, a certain constraint is added when thedescription is generated, that is, the FEC redundancy of each datasource block cannot be decreased when the packet loss rate increases;then, these FEC description information is added into the stream fortransmission, or is transmitted to the data forwarding node separately.

For the data forwarding node, the data forwarding node may adjust,according to the respective packet loss rates of the source transmissionnetwork and the target transmission network as well as the FECdescription information corresponding to the source stream, the forwarderror correction redundancy for each data source block in the sourcestream to obtain an error tolerance stream compliant with the packetloss rate of the target transmission network. Specifically, if the firstpacket loss rate corresponding to the source transmission network isless than the second packet loss rate corresponding to the targettransmission network, the corresponding forward error correctionredundancy is added on the basis of the forward error correctionredundancy carried in each data source block in the source streamaccording to the FEC description information; if the first packet lossrate corresponding to the source transmission network is greater thanthe second packet loss rate corresponding to the target transmissionnetwork, the corresponding forward error correction redundancy isdiscarded on the basis of the forward error correction redundancycarried in each data source block in the source stream according to theFEC description information. If the first packet loss rate correspondingto the source transmission network is equal to the second packet lossrate corresponding to the target transmission network, the data may beforwarded directly without any processing.

FIG. 10 is a schematic diagram of using forward error correctiondescription information for FEC redundancy allocation according to amethod embodiment of the present invention. FIG. 10 shows an applicationexample of FEC description information in a video transmission system:The video server generates a video stream that carries the FECdescription information, The FEC description information indicates theFEC redundancy that needs to be added in each video data source blockunder a given packet loss rate. The data forwarding node arrangesdifferent redundancy rate for each video data source block according tothe packet loss rate of the subsequent transmission network to implementunequal FEC protection. In the example shown in FIG. 10, a GOP videodata packet is divided into three data source blocks (indicated by thewhite part in FIG. 10). Different redundancy (indicated by the grey partin FIG. 10) is added for different data source blocks respectively. Inthis way, all streams that are transmitted through the data forwardingnode may reach the best performance under the current packet loss rate,and the operation complexity is relatively low.

In the method provided in this embodiment, the data server may have theerror tolerance aid information for describing the FEC allocation ofdata carried in the sent stream, or send the error tolerance aidinformation separately, so that the relevant data node can performdifferent FEC protections on the data sources of different importancelevels according to the error tolerance aid information, which not onlyensures reliability of data transmission, but also improves usage of thebandwidth resource.

FIG. 11 is a schematic structure diagram of a data forwarding nodedevice according to an embodiment of the present invention. As shown inFIG. 11, the data forwarding node is connected to different networks,and is capable of storage and calculation to some extent, and may be adevice such as a streaming server, a media gateway, and a router. Thedata forwarding node includes a first receiving module 11, a codingprocessing module 12, and a first sending module 13. The first receivingmodule 11 is configured to receive a source stream sent from a sourcetransmission network to a target transmission network; the codingprocessing module 12 is configured to perform error tolerance codingprocessing on the source stream according to respective packet lossrates of the source transmission network and the target transmissionnetwork as well as error tolerance aid information corresponding to thesource stream to obtain an error tolerance stream; and the first sendingmodule 13 is configured to send the obtained error tolerance stream tothe target transmission network.

Specifically, according to the packet loss rates corresponding to atleast two transmission networks in the data transmission network systemof the data forwarding node, the data server obtains the error toleranceaid information corresponding to the source stream, and sends the errortolerance aid information to the data forwarding node, and then the dataforwarding node receives the error tolerance aid information through thefirst receiving module 11. When the network is constructed, the dataforwarding node already acquires the respective packet loss rates of thesource transmission network and the target transmission network.Therefore, after the first receiving module 11 receives the sourcestream sent by the data server, the coding processing module 12 performsfast transcoding on the source stream according to the respective packetloss rates of the source transmission network and the targettransmission network, and with reference to the error tolerance aidinformation, uses the error tolerance aid information to quicklygenerate the error tolerance stream compliant with the subsequentnetwork packet loss characteristics, makes fast response to a change ofthe packet loss rate, and changes the error tolerance capability of thestream according to actual conditions, for example, adjusts the streamredundancy rate and the FEC protection strength according to actualconditions. After obtaining the error tolerance stream, the codingprocessing module 12 uses the first sending module 13 to send the errortolerance stream to the terminal device or other data forwarding nodesthrough the target transmission network.

Further, the coding module 12 may adjust the stream redundancy rate andthe FEC protection strength according to the error tolerance aidinformation, which may be specifically completed through. at least onesubmodule included in the coding processing module 12, and include thefollowing:

The first processing submodule 121 is configured to adjust redundantframes adaptively for multiple data frames included in the source streamaccording to the respective packet loss rates of the source transmissionnetwork and the target transmission network as well as the errortolerance aid information corresponding to the source stream to obtainan error tolerance stream. The error tolerance aid information includesdescription information about the redundant frame sets corresponding tothe respective packet loss rates of the source transmission network andthe target transmission network. The redundant frame sets are configuredto identify data frames whose redundant frames need to be generatedamong multiple data frames in the source stream. Each redundant frameset that is indicated by the description information meets the followingcondition: A redundant frame set corresponding to a low packet loss rateis a subset of a redundant frame set corresponding to a high packet lossrate. This embodiment does not need to perform very complicatedtranscoding on the stream; the data forwarding node stores the errortolerance aid information under each packet loss rate, and then uses theinformation to implement scalable redundancy allocation. The stream ofthe highest coding efficiency may be transmitted in a wired network, andthe redundant frames are added or deleted quickly by the data forwardingnode according to the error tolerance aid information.

The second processing submodule 122 is configured to adjust forwarderror correction redundancy for data source blocks in the source streamaccording to the respective packet loss rates of the source transmissionnetwork and the target transmission network as well as error toleranceaid information corresponding to the source stream to obtain an errortolerance stream. The error tolerance aid information includes forwarderror correction description information about forward error correctionsets corresponding to respective packet loss rates of the sourcetransmission network and the target transmission network respectively.The forward error correction set includes the forward error correctionredundancy that needs to be allocated to each data source block underdifferent packet loss rates, and each forward error correction set thatis indicated in the forward error correction description informationmeets the following condition: A forward error correction setcorresponding to a low packet loss rate is a subset of a forward errorcorrection set corresponding to a high packet loss rate. The dataforwarding node in this embodiment may be a device such as a streamingserver, a media gateway, and a router.

The data forwarding node provided in this embodiment can perform,according to the error tolerance aid information sent by the data serverand corresponding to the data stream, error tolerance coding processingon the stream that needs to be forwarded to obtain an error tolerancestream that is adaptable to the network characteristics of the packetloss rate of the subsequent transmission network. This embodiment makesfull and proper use of network resources, makes fast response to everychange, and changes the error tolerance capability of the streamaccording to actual conditions.

FIG. 12 is a schematic structure diagram of a network device accordingto a first embodiment of the present invention. As shown in FIG. 12, thenetwork device includes a first obtaining module 21 and a second sendingmodule 22. The first obtaining module 21 is configured to obtain errortolerance aid information corresponding to a source stream according topacket loss rates corresponding to at least two transmission networks ina data transmission network system before sending the source stream tothe data transmission network system, where the error tolerance aidinformation is used by a data forwarding node in the data transmissionnetwork system to perform error tolerance coding processing on thereceived stream to obtain an error tolerance stream for reference; andthe second sending module 22 is configured to send the error toleranceaid information to the data forwarding node.

Specifically, before sending a video stream to a certain data forwardingnode in the data transmission network system, the network device needsto obtain the error tolerance aid information corresponding to the sentstream through the first obtaining module 21. The error tolerance aidinformation is used by the data forwarding node in the data transmissionnetwork system to perform error tolerance coding processing on thereceived stream to obtain the error tolerance stream adaptable to thepacket loss rate corresponding to the subsequent transmission network.That is to say, the data forwarding node can perform quick transcodingaccording to the error tolerance aid information to adapt to the packetloss rate of the subsequent transmission network of the data forwardingnode, and uses the error tolerance aid information to quickly generatethe error tolerance stream compliant with the subsequent network packetloss characteristics. After obtaining the error tolerance stream, thefirst obtaining module 21 sends the error tolerance aid information toeach data forwarding node in the data transmission network systemthrough the second sending module 22 for the data forwarding node toperform error tolerance coding. The error tolerance aid information maybe carried in the stream or sent separately.

The network device provided in this embodiment may be the data serverinvolved in the foregoing embodiments. The network device obtains errortolerance aid information corresponding to the to-be-sent streamaccording to packet loss rates corresponding to at least twotransmission networks in the data transmission network system, and sendsthe error tolerance aid information to the data forwarding node.Therefore, according to different packet loss rates of transmissionnetworks, the data forwarding node can use the error tolerance aidinformation to quickly generate the error tolerance stream compliantwith the packet loss characteristics of the subsequent transmissionnetwork, which improves the error tolerance capability of streams innetwork environments with different packet loss rates.

FIG. 13 is a schematic structure diagram of a network device accordingto a second embodiment of the present invention. As shown in FIG. 13,the network device includes a first obtaining module 21 and a secondsending module 22. The first obtaining module 21 includes at least oneof submodules in the following, where the submodule includes thefollowing:

A first obtaining submodule 211 is configured to obtain, according tothe packet loss rates corresponding to at least two transmissionnetworks in the data transmission network system, error tolerance aidinformation for the data forwarding node to adjust redundant framesadaptively for the received stream to obtain an error tolerance stream.The error tolerance aid information includes description informationabout the redundant frame sets corresponding to the respective packetloss rates of the at least two transmission networks in the datatransmission network system respectively. The redundant frame sets areconfigured to identify data frames whose redundant frames need to begenerated among multiple data frames in the stream. Each redundant frameset that is indicated by the description information meets the followingcondition: A redundant frame set corresponding to a low packet loss rateis a subset of a redundant frame set corresponding to a high packet lossrate.

A second obtaining submodule 212 is configured to obtain, according tothe packet loss rates corresponding to at least two transmissionnetworks in the data transmission network system, the error toleranceaid information for the data forwarding node to adjust forward errorcorrection redundancy for each data source block in the received streamto obtain an error tolerance stream. The error tolerance aid informationincludes forward error correction description information about theforward error correction sets corresponding to the respective packetloss rates of the at least two transmission networks in the datatransmission network system respectively. The forward error correctionset includes the forward error correction redundancy that needs beallocated to each data source block under different packet loss ratesrespectively. Each forward error correction set that is indicated by theforward error correction description information meets the followingcondition: A forward error correction set corresponding to a low packetloss rate is a subset of a forward error correction set corresponding toa high packet loss rate.

In addition, the second sending module 22 in the network device providedin this embodiment is further configured to send the error tolerancestream together with the error tolerance aid information to the dataforwarding node after generating the error tolerance streamcorresponding to the source stream according to the error tolerance aidinformation and the packet loss rate corresponding to the transmissionnetwork between the data forwarding nodes.

The network device provided in this embodiment may be the data serverinvolved in the foregoing embodiments. The network device obtains theerror tolerance aid information corresponding to the to-be-sent streamaccording to the packet loss rates corresponding to at least twotransmission networks in the data transmission network system, andtherefore, the data forwarding node can use the error tolerance aidinformation to quickly generate the error tolerance stream compliantwith the packet loss characteristics of the subsequent transmissionnetwork according to different packet loss rates of transmissionnetworks, which improves the error tolerance capability of streams innetwork environments with different packet loss rates. Moreover, thedelay is short, and the operation complexity is low, which are conduciveto real-time application.

FIG. 14 is a schematic composition diagram of a network system accordingto an embodiment of the present invention. As shown in FIG. 14, thenetwork system includes a network device 1, a data forwarding nodedevice 2, and a terminal device 3. The data forwarding node device 2 isconfigured to: receive a source stream sent from a source transmissionnetwork to a target transmission network; perform error tolerance codingon the source stream according to respective packet loss rates of thesource transmission network and the target transmission network as wellas error tolerance aid information corresponding to the source stream toobtain an error tolerance stream; and send the obtained error tolerancestream to the target transmission network; and the network device 1 isconfigured to: obtain error tolerance aid information corresponding to asource stream according to packet loss rates corresponding to at leasttwo transmission networks in a data transmission network system beforesending the source stream to the data transmission network system; andsend the error tolerance aid information to the data forwarding node,where the error tolerance aid information is used by the data forwardingnode in the data transmission network system to perform error tolerancecoding processing on the received stream to obtain an error tolerancestream for reference.

The network device 1 provides a data source, and the data forwardingnode device 2 is configured to forward the data to be sent to theterminal device 3, makes fast response to every change, changes theerror tolerance capability of the stream according to actual conditions,and uses the error tolerance aid information to quickly generate theerror tolerance stream compliant with the packet loss characteristics ofthe subsequent network. The network system further includes multipletransmission networks 4, which are respectively set between the networkdevice 1, the data forwarding node device 2, and the terminal device 3,and are configured to provide data transmission channels between thenetwork device 1, the data forwarding node device 2, and the dataforwarding node device 3. The data forwarding node device and thenetwork device in the network system provided in this embodiment may bethe data forwarding node device and the network device provided in theforegoing embodiments respectively. For the structures and functions ofthe data forwarding node device and the network device, reference may bemade to the description in the foregoing embodiments, and details arenot described here again. The data forwarding node in the embodiment ofthe present invention may be a device such as a streaming server, amedia gateway, and a router; and the network device in this embodimentmay be the data server involves in the foregoing embodiments.

In the network system provided in this embodiment, the network deviceobtains the error tolerance aid information corresponding to theto-be-sent stream according to the packet loss rates corresponding to atleast two transmission networks in the data transmission network system,and therefore, the data forwarding node can use the error tolerance aidinformation to quickly generate the error tolerance stream compliantwith the packet loss characteristics of the subsequent transmissionnetwork according to different packet loss rates of transmissionnetworks, which improves the error tolerance capability of streams innetwork environments with different packet loss rates. Moreover, thedelay is short, and the operation complexity is low, which are conduciveto real-time application.

Persons of ordinary skill in the art may understand that all or a partof the steps of the method according to the embodiments of the presentinvention may be implemented by a program instructing relevant hardware.The program may be stored in computer readable storage media. When theprogram runs, the steps of the method according to the embodiments ofthe present invention are performed. The storage media may be any mediacapable of storing program codes, such as a ROM, a RAM, a magnetic disk,or an optical disk.

Finally, it should be noted that: the above embodiments are merelyprovided for illustrating the technical solutions of the presentinvention, but are not intended to limit the present invention. Personsof ordinary skill in the art should understand that, although thepresent invention has been described in detail with reference to theforegoing embodiments, modifications may still be made to the technicalsolutions described in the foregoing embodiments, or equivalentreplacements can be made to some technical features in the technicalsolutions, and these modifications or replacements do not cause theessence of corresponding technical solutions to depart from the spiritand scope of the technical solutions of the embodiments of presentinvention.

What is claimed is:
 1. A video data transmission processing method,comprising performing by a data forwarding node device, the following:receiving through a source transmission network, a source stream sentfrom a data server to a target transmission network; performing errortolerance coding processing on the source stream to obtain an errortolerance target stream to be sent to the target transmission network,wherein the error tolerance coding processing is according to:respective packet loss rates of both the source transmission network andthe target transmission network, and error tolerance aid informationcorresponding to the source stream sent from the data server; andsending the obtained error tolerance target stream to the targettransmission network.
 2. The video data transmission processing methodaccording to claim 1, wherein: the error tolerance aid informationcomprises description information about error tolerance data sets thatrespectively correspond to the respective packet loss rates of thesource transmission network and the target transmission network, and theerror tolerance data sets are configured to identify error tolerancedata that needs to be adjusted in the source stream.
 3. The video datatransmission processing method according to claim 2, wherein: each errortolerance data set that is indicated by the description informationmeets the following condition: an error tolerance data set correspondingto a low packet loss rate is a subset of an error tolerance data setcorresponding to a high packet loss rate.
 4. The video data transmissionprocessing method according to claim 2, wherein: the performing of theerror tolerance coding processing on the source stream according to therespective packet loss rates of the source transmission network and thetarget transmission network, and error tolerance aid informationcorresponding to the source stream from the data server, in order toobtain an error tolerance stream, comprises: according to the respectivepacket loss rates of the source transmission network and the targettransmission network, and the error tolerance aid informationcorresponding to the source stream: adjusting by the data forwardingnode device, redundant frames for multiple data frames included in thesource stream to obtain the error tolerance stream, wherein the errortolerance data set is a redundant frame set that is configured toidentify data frames whose redundant frames need to be generated amongmultiple data frames in the source stream.
 5. The video datatransmission processing method according to claim 4, wherein: theadjusting, according to the respective packet loss rates of the sourcetransmission network and the target transmission network, and the errortolerance aid information corresponding to the source stream from thedata server, and the redundant frames for the multiple data framesincluded in the source stream, comprises: if a first packet loss ratecorresponding to the source transmission network is less than a secondpacket loss rate corresponding to the target transmission network:adding by the data forwarding node device, redundant frames which existin a second redundant frame set but do not exist in a first redundantframe set into the source stream that carries the redundant framecorresponding to the first packet loss rate according to the firstredundant frame set corresponding to the first packet loss rate and thesecond redundant frame set which corresponds to the second packet lossrate that are indicated in the description information; or if the firstpacket loss rate corresponding to the source transmission network isgreater than the second packet loss rate corresponding to the targettransmission network: discarding by the data forwarding node device,redundant frames which exist in the first redundant frame set but do notexist in the second redundant frame set from the source stream thatcarries the redundant frame corresponding to the first packet loss rateaccording to the first redundant frame set which corresponds to thefirst packet loss rate and the second redundant frame set correspondingto the second packet loss rate that are indicated in the descriptioninformation.
 6. The video data transmission processing method accordingto claim 2, wherein: the performing of the error tolerance codingprocessing on the source stream according to the respective packet lossrates of the source transmission network and the target transmissionnetwork, and error tolerance aid information corresponding to the sourcestream from the data server, in order to obtain an error tolerancestream, comprises: according to the respective packet loss rates of thesource transmission network and the target transmission network, and theerror tolerance aid information corresponding to the source stream:adjusting by the data forwarding node device, forward error correctionredundancy for each data source block in the source stream to obtain theerror tolerance stream, wherein the error tolerance data set is aforward error correction set, and the forward error correction setcomprises forward error correction redundancy that needs to be allocatedto each data source block under different packet loss rates.
 7. Thevideo data transmission processing method according to claim 6, wherein:the adjusting, according to the respective packet loss rates of thesource transmission network and the target transmission network, and theerror tolerance aid information corresponding to the source stream fromthe data server, and the forward error correction redundancy for eachdata source block in the source stream, comprises: if a first packetloss rate corresponding to the source transmission network is less thana second packet loss rate corresponding to the target transmissionnetwork: adding by the data forwarding node device, correspondingforward error correction redundancy on the basis of forward errorcorrection redundancy carried in each data source block in the sourcestream according to the forward error correction descriptioninformation; or if the first packet loss rate corresponding to thesource transmission network is greater than the second packet loss ratecorresponding to the target transmission network: discarding by the dataforwarding node device, corresponding forward error correctionredundancy on the basis of forward error correction redundancy carriedin each data source block in the source stream according to the forwarderror correction description information.
 8. The video data transmissionprocessing method according to claim 1, wherein the method furthercomprises: forwarding the error tolerance aid information together withthe error tolerance stream or separately.
 9. A video data sendingprocessing method, comprising: prior to sending a received source streamto a data transmission network system, obtaining by a data server, errortolerance aid information corresponding to the received source streamaccording to packet loss rates corresponding to at least twotransmission networks which are comprised in the data transmissionnetwork system, wherein the error tolerance aid information is used by adata forwarding node device in the data transmission network system toperform error tolerance coding processing on the received source streamaccording to the obtained packet loss rates and the error tolerance aidinformation to obtain an error tolerance target stream for reference;and sending by the data server, the error tolerance aid information tothe data forwarding node device.
 10. The video data sending processingmethod according to claim 9, wherein the sending the error tolerance aidinformation to the data forwarding node device comprises: aftergenerating the error tolerance stream corresponding to the source streamaccording to the error tolerance aid information and packet loss ratescorresponding to transmission networks between data forwarding nodedevices, sending the error tolerance stream together with the errortolerance aid information to the data forwarding node device.
 11. Thevideo data sending processing method according to claim 9, wherein: theerror tolerance aid information comprises description information abouterror tolerance data sets that respectively correspond to the respectivepacket loss rates of at least two transmission networks in the datatransmission network system, and the error tolerance data sets areconfigured to identify error tolerance data that needs to be adjusted inthe source stream.
 12. The video data sending processing methodaccording to claim 11, wherein: each error tolerance data set that isindicated by the description information which meets the followingcondition: an error tolerance data set corresponding to a low packetloss rate is a subset of an error tolerance data set corresponding to ahigh packet loss rate.
 13. The video data sending processing methodaccording to claim 11, wherein: the obtaining the error tolerance aidinformation corresponding to the source stream according to the packetloss rates corresponding to at least two transmission networks in thedata transmission network system, comprises: obtaining by the dataserver, according to the packet loss rates corresponding to the at leasttwo transmission networks in the data transmission network system, theerror tolerance aid information for the data forwarding node to adjustthe received stream to obtain an error tolerance stream, wherein theerror tolerance data set is a redundant frame set that is configured toidentify data frames whose redundant frames need to be generated amongmultiple data frames in the source stream; or obtaining by the dataserver, according to the packet loss rates corresponding to at least twotransmission networks in the data transmission network system, the errortolerance aid information for the data forwarding node device to adjustforward error correction redundancy for each data source block in thereceived stream to obtain the error tolerance stream, wherein the errortolerance data set is a forward error correction set, and the forwarderror correction set comprises forward error correction redundancy thatneeds to be allocated to each data source block under different packetloss rates.
 14. The video data sending processing method according toclaim 13, wherein: the obtaining, according to the packet loss ratescorresponding to at least two transmission networks in the datatransmission network system, the error tolerance aid information for thedata forwarding node device to adjust redundant frames for the receivedstream to obtain the error tolerance stream, comprises: calculating bythe data server, source distortion information and channel distortioninformation corresponding to each data frame in the stream with respectto at least two packet loss rates in a case of generating no redundantframe and in a case of generating redundant frames respectively;applying by the data server, a rate-distortion model to judge whetherredundant frames of data frames corresponding to the calculated sourcedistortion information and channel distortion information need to begenerated under a corresponding packet loss rate condition to obtain ajudgment result; and obtaining description information about redundantframe sets corresponding to the at least two packet loss ratesrespectively according to the judgment result.
 15. A data forwardingnode device, comprising: a first receiving module, configured to receivethrough a source transmission network, a source stream sent from a dataserver to a target transmission network; a coding processing module,configured to perform error tolerance coding on the source stream toobtain an error tolerance target stream to be sent to the targettransmission network, wherein the error tolerance coding processing isaccording to respective packet loss rates of both the sourcetransmission network and the target transmission network, and errortolerance aid information corresponding to the source stream sent fromthe data server; and a first sending module, configured to send theobtained error tolerance target stream to the target transmissionnetwork.
 16. The data forwarding node device according to claim 15,wherein the coding processing module comprises: a first processingsubmodule, configured to adjust redundant frames for multiple dataframes included in the source stream according to the respective packetloss rates of the source transmission network and the targettransmission network the error tolerance aid information correspondingto the source stream to obtain an error tolerance stream, wherein theerror tolerance aid information comprises description information aboutredundant frame sets corresponding to the respective packet loss ratesof the source transmission network and the target transmission networkrespectively, and the redundant frame sets are configured to identifydata frames whose redundant frames need to be generated among multipledata frames in the source stream; or a second processing submodule,configured to adjust forward error correction redundancy for each datasource block in the source stream according to the respective packetloss rates of the source transmission network and the targettransmission network the error tolerance aid information correspondingto the source stream to obtain an error tolerance stream, wherein theerror tolerance aid information comprises forward error correctiondescription information about forward error correction setscorresponding to the respective packet loss rates of the sourcetransmission network and the target transmission network respectively,and the forward error correction set comprises forward error correctionredundancy that needs to be allocated to each data source block underdifferent packet loss rates respectively.
 17. The data forwarding nodedevice according to claim 16, wherein: each redundant frame set that isindicated by the description information meets the following condition:a redundant frame set corresponding to a low packet loss rate is asubset of a redundant frame set corresponding to a high packet lossrate; or each forward error correction set that is indicated by theforward error correction description information meets the followingcondition: a forward error correction set corresponding to a low packetloss rate is a subset of a forward error correction set corresponding toa high packet loss rate.
 18. A network device, comprising: a firstobtaining module, configured to obtain error tolerance aid informationcorresponding to a source stream according to packet loss ratescorresponding to at least two transmission networks in a datatransmission network system before sending the source stream to the datatransmission network system, wherein the error tolerance aid informationis used by a data forwarding node device in the data transmissionnetwork system to perform error tolerance coding processing on thereceived stream to obtain an error tolerance stream for reference; and asecond sending module, configured to send the error tolerance aidinformation to the data forwarding node device.
 19. The network deviceaccording to claim 18, wherein the first obtaining module comprises: afirst obtaining submodule, configured to: obtain, according to thepacket loss rates corresponding to at least two transmission networks inthe data transmission network system, the error tolerance aidinformation for the data forwarding node to adjust redundant frames fora received stream to obtain an error tolerance stream, and the errortolerance aid information comprises: description information aboutredundant frame sets corresponding to the respective packet loss ratesof at least two transmission networks in the data transmission networksystem respectively, and the redundant frame sets are configured toidentify data frames whose redundant frames need to be generated amongmultiple data frames in the stream; or a second obtaining submodule,configured to: obtain, according to the packet loss rates correspondingto the at least two transmission networks in the data transmissionnetwork system, the error tolerance aid information for the dataforwarding node to adjust forward error correction redundancy for eachdata source block in the received stream to obtain an error tolerancestream, wherein the error tolerance aid information comprises forwarderror correction description information about forward error correctionsets corresponding to the respective packet loss rates of the at leasttwo transmission networks in the data transmission network systemrespectively, and the forward error correction set comprises forwarderror correction redundancy that needs to be allocated to each datasource block under different packet loss rates respectively.
 20. Thenetwork device according to claim 19, wherein: each redundant frame setthat is indicated by the description information meets the followingcondition: a redundant frame set corresponding to a low packet loss rateis a subset of a redundant frame set corresponding to a high packet lossrate; or each forward error correction set that is indicated by theforward error correction description information meets the followingcondition: a forward error correction set corresponding to a low packetloss rate is a subset of a forward error correction set corresponding toa high packet loss rate.
 21. A network system, comprising: a dataforwarding node device, configured to: receive a source stream sent froma data server to a target transmission network; perform error tolerancecoding on the source stream according to: respective packet loss ratesof both the source transmission network and the target transmissionnetwork, and error tolerance aid information corresponding to the sourcestream sent from the data server to obtain an error tolerance stream;and send the obtained error tolerance stream to the target transmissionnetwork; and a network device, configured to: obtain error tolerance aidinformation corresponding to a source stream according to packet lossrates corresponding to at least two transmission networks in a datatransmission network system before sending the source stream to the datatransmission network system; and send the error tolerance aidinformation to the data forwarding node device, wherein the errortolerance aid information is used by the data forwarding node device inthe data transmission network system to perform error tolerance codingprocessing on the received stream to obtain an error tolerance streamfor reference.